Typical solid electrolytes used for high temperature sodium cells utilize a solid ceramic .beta."-Al.sub.2 O.sub.3 sealed end tube into which either the anode or cathode component is added. The disadvantage of this cell design is that the .beta."-Al.sub.2 O.sub.3 tubes are rigid ceramics, that by their nature are brittle and easily cracked when stretched. In addition, because the tubes are fragile, the thickness of the tubes must be made relatively large (&gt;0.5 mm) so as to provide for a margin of safety should the separator fail once the cell was molten at the high operating temperatures of greater than 200.degree. C.